Benthic nitrogen fixation was investigated in Kaneohe Bay, Oahu,
Hawaiian Islands, which receives secondary sewage from two treatment plants.
The range of nitrogen fixation rates (2 to 10 ng N2g-l hr-l) was similar to those
reported by other workers for a variety of benthic systems. Enrichment cultures
prepared from sediment samples from five stations revealed the existence of several
distinct physiological types of nitrogen-fixing bacteria. It was found that 50 percent
of the bacterial fixation in the southern sector was light-dependent. There was a
significant relationship between the numbers of nitrogen-fixing bacteria detected
and rates of nitrogen fixation measured in the sediments.